Kerbal Space Program

I can replicate this here with the attached craft file and have seen numerous reports on the forums/reddit of simlar.

I've been trying to make sense of this phenomenon and can't quite find a common cause. The only factor that does seem apparent is the orientation of the assembly on the launchpad.

Another report #5190 has come in with very similar results. I have distilled the assembly down to the minimal parts required to trigger the bug, and attached here.
Test 4 - minimal

Depending on the orientation of the vessel, the docking port will explode. It only explodes when aligned north/south and only with the other attached parts. Using other parts does not cause the bug. Rotating the craft just a few degrees prevents the bug.

Taking the orientation aspect further, I added enough reaction wheels and power to be able to rotate the vessel in place on the pad. Launching and immediately rotating the craft does not prevent the overheat.
Test 4 - dynamic

This assembly from #5174 does not have an orientation aspect to it and will explode regardless. Both nodes of the octagonal strut must be occupied, and either a pair of TR-2L or XL3 wheels attached to the sides.
Thermal Runaway

Clipping does not appear to be a factor but has been avoided. The thermal runaway happens during the day and the night.

Please help us identify which part combinations and orientations trigger this bug? The more examples we have, the better chance of identifying a common factor.

I came here to report an instance of the same kind of bug, with 3x solar panels attached to cubic octagonal strut (COS) adjacent to a HECS probe core (HECS PC), there is overheating in the panels and the COS then explodes on the launch pad (checked in F3) using x4 time compression. Yet with two panels there is no heating, with 4x panels overheating is even quicker.

If three COS are attached to the HECS PC and 3x panels are attached to the middle COS overheating occurs but there is no explosion.

Appears to be a cumulative heating imbalance related to solar panel heat production with the panel connection to the COS causing the heat to accumulate when it should not, plus the COS connection to the adjacent HECS PC causing a cooling conduction failure for some reason which exacerbates the heat build up enough to cause explosion.

When you attach 6x panels to the HECS probe core it is fine at x4 time warp so it is not the HECS PC itself.

So the girder in the OP might have a comparable issue, apparently some connections do not conduct heat well enough. This applies to the octagonal strut as well as the cubic octagonal strut.

Screenshot 37 explodes
Screenshot 43 does not explode

I'm new to the bugtracker so I hope I'm doing this right.

Yesterday I wrote a bug report for this bug, but I hadn't searched well enough to see that it's already been reported here so I'll repost my observations about the bug here.

This is a bug I've seen a lot before, and it happens to me in both the stock game and with mods.

Sometimes, some parts will overheat and explode instantly for no reason. This has most recently happened to me on a mission to Duna, I decoupled the transfer stage to land with just my lander (which I forgot the legs on, oops!) and the decoupler that attached the command pod to the lander exploded due to overheating, despite the craft going at around 6m/s. I know it's overheating because I checked the F3 flight log and that's what it said.

If I enable the debug menu's 'Ignore max temperature' and then decouple the transfer stage, I can see a sudden rapid temperature rise in every part of the craft, I assume it originates from the buggy decoupler.

I said I've experienced this bug a lot, so I'll tell you what I think is causing it - I can get this bug to consistently happen when there are small parts clipped into other small parts, even if the attachment nodes allow it and I haven't even touched the offset tool at all. I can get this to happen all the time with docking ports inside the small Rockomax adapter (the docking port model clips inside the adapter) and with the Duna mission glitch I explained, I think it's happening because the decoupler is clipped inside a heatshield that's attached to the pod. This might not be the case though - this is just a hunch I have.

I've attached a .zip file of an entire save file that you can use to re-create this glitch for yourself. The save file comes with two stock crafts that both experience the glitch (if I've accidentally used a part that isn't in the stock game, let me know and I'll update the craft file). Here's a video of the bug in action: https://youtu.be/c-hhwFJRZmM You can re-create these events with the save file.

As noted in Bug #5305, http://forum.kerbalspaceprogram.com/threads/129800-Craft-exploding-while-passing-over-poles?p=2126521#post2126521 might be related.
Summary: Crafts passing over the south pole overheat instantly and explode. Because you need to be pretty accurate setting up your polar orbit and this only happens if the craft is active, chances of hitting this by accident are pretty low.
This image http://i.imgur.com/1aqh939.jpg ("Ignore Max Temp") seems to indicate a runaway heat iusse. I also attached a log file.

I uploaded an ordinary zip file. When you try to download it, make sure anything marked "accelerator" is unchecked; that's usually what it is in my experience across a great many sites. The zip file is 4093K. The persistent.sfs file attached I think. Let me know if you need anything else.

Since then, I've done a test in a sandbox game to determine if the effect is similar to solar heating in a craft called "Solar Polar Explodar" in the quicksave #1 file, using a 3.75m heatshield to shade an otherwise 1.25m spacecraft. After deploying the thermal alpaca from Alt-F12 to keep it from explodaring, I found the opposite was the case: relative temperature colors from Hot Spot showed the engine, right at the back, to be hottest at at least 3.5E+35 K (2900x Planck Temperature) initially. As it cooled down, I noticed some very odd behaviours:

- temperatures would go down by an order of magnitude roughly every 6 minutes of game time at 4X time acceleration. (A similar craft orbiting Earth in real-life made of appropriate handwavium to survive and radiate properly at these temperatures would probably cool to a few hundred thousand K in the first frame- er. 0.04sec, emitting enough energy to vaporize the entire solar system, and confuse the heck out of my friend in M87 who has a gamma ray telescope similar to Fermi.)
- the difference between skin and internal temperatures was a constant factor depending on the part and time acceleration. This corrected at about 4000K as the craft cooled. At faster time acceleration, the difference would be smallest and the cooling rates highest. (Conductive heat transfer rates go as the difference in temperature, so, given the first point wackiness, this is probably normal other than the time acceleration effects.)
- Above about 30000K (much less for the large radiators), anomalous internal heat was generated, especially at 5x and greater time accelerations. Before cooling to about 20000K craft average (I didn't explore this exhaustively), going to 5x or higher time acceleration caused temperatures to increase. This and the previous point is why I ran most of the cooling at 4X.
- Above about 1600K (high normal temperatures), the large radiator generated an anomalous 12500kW internal heat when deployed. For most of the final phase of cooling, it worked better stowed as a result! As it cooled below 1600K, this 12.5MW internal heating would flicker on and off between zero and 12.5MW, never a value between. Internal rates on other parts, and when the radiators were absurdly hot, didn't quantize like this as far as I could tell.
- You've probably figured out that I did a maneuver to avoid the poles a quarter of an orbit after the first polar encounter.

This the simplest case I've noticed so far of a surface temperature freezing up. The craft is a Mk1 Command Pod topped by an OCTO topped by a Mk16 parachute. (It's a rescue/tourism craft returning to Kerbin after just under half an orbit; I could easily beat the "Satellite Catch" reddit challenge if I gave enough of a [insert favorite derogative].) Numbers are exposed by Hot Spot, and as you can see from all the KER HUDs, I'm taking full advantage of the latest version of Kerbal Engineer. The parachute is selected in preparation for chute opening. The radiative cooling from this part is 3.34kW, which strikes me as rather high just by instinct. But I can do math. The exposed surface area is 0.415m2 max, and the emissivity given in the part file is 0.7, enough that spectralcalc.com can give me pretty precise numbers. With the given surface temperature, it should be radiating 253.8W. At the internal temperature of 411.97K, it should be 474.5W. The temperature needed to radiate the displayed value is 671.03K. As for the tiny value displayed by KER, which is (I think) supposed to be the whole craft, 48.37W, the parachute on its own would need to be a frigid 186.84K to radiate that on its own (I've only seen kerbals get that cold: for whatever reason, they pop out of the hatch into EVA at absolute zero.) If you need help with the math, I know some of the equations and know how to find the rest, but Fractal_UK, if you can find him, probably has them memorized.

I found a part combination, that overheats no matter the orientation or root part. A closed CRG-50 cargo bay with ADTP-2-3s on each end, and fuel tanks on the ADTP-2-3s or other parts with high thermal mass.
Video: https://www.youtube.com/watch?v=UchYJPtyCyE
Pic: http://i.imgur.com/uUPPzpk
Logs: https://drive.google.com/file/d/0B34u1G2080ndU1JDR1lJbkptTWc/view

All test cases have now been fixed. Thank you to all that provided valuable information in tracing this down.